Alkylation process

ABSTRACT

A side-chain of a substituted aromatic compound is alkylated by reacting the aromatic compound with an alkylating agent in the presence of a catalyst. The catalyst comprises a restructured smectite clay to which basic ions are incorporated by ion-exchange. The restructuring of the smectite clay is carried out by acid-treating the clay prior to ion-exchange.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/FI01/00085 filed on29 Jan. 2001. Priority is claimed on that application and on thefollowing application: Country: Finland, Application No. 20000183,Filed: 28 Jan. 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to alkylation or alkenylation of the sidechain of substituted aromatic compounds. In particular, the presentinvention comprises a process for alkylating the side-chain of xylenewith a C₄-alkylene or diene.

The present invention also relates to a novel catalyst comprising arestructured clay.

2. Description of Related Art

The alkylation (or alkenylation) of side-chain(s) of alkyl-substitutedaromatic hydrocarbons by aliphatic olefins is carried out in thepresence of a basic catalyst. An acidic substance, on the other hand,catalyses the alkylation of the benzene ring. Typically, the alkylationreaction is carried out batch-wise or in a fixed-bed reactor in atmoderate to high temperatures. In the batch reactor the catalyst isusually present as a slurry.

In prior art, the basic catalysts have typically comprised an alkalimetal, optionally on a carrier. Sodium and potassium are the most widelyused alkali metals (e.g. H. Pines, J.A.C.S., 1955, 77, 5), and the mosttypical carriers have been magnesia and alumina, although early examplesof the catalysts used for side-chain alkylation include sodium-loadedpotassium phosphate (U.S. Pat. No. 5,347,062). U.S. Pat. No. 5,118,895discloses a catalyst comprising potassium on magnesia and U.S. Pat. No.5,097,088 discloses a catalyst comprising potassium on magnesia-alumina.

The obvious problem with using metallic alkali metals is theirreactivity. It is generally known that alkali metals react vigorouslywith even small amounts of water. Thus, the use of metallic metalcatalysts in an industrial scale process sets very strict requirementsto the handling of the starting materials and process operation.

Alumina is useful as a carrier due to its high surface area enabling agood dispersability of the loaded metal. Nevertheless, because of theacidic nature of the alumina, a catalyst comprising conventionallyproduced alumina as a carrier cannot provide sufficient activity foralkylating the side-chain of aromatic compounds.

On the contrary, a high activity is achieved when a catalyst comprisingan alkali metal loaded on a basic carrier is used. For example,alkali-metal impregnated on supports such as Na-exchanged zeolite havebeen suggested in prior art, but the yields of alkylated productremained extremely low. Thus, the activity of basic catalysts does notresult in high yields of reaction products. It can thus be concludedthat the basic carriers used to date have been of low surface area andthe alkali metal loaded on them is not sufficiently dispersed.

Further, when the catalyst is active enough, problems of a differentkind may occur. For example, if the alkylbenzene which is alkylated hasmore than one side-chain, it is probable that both these side-chains arealkylated—via continued reaction of the alkylating agent present withinitial reaction product formed. In some cases the desired product mustbe removed from the catalyst.

An attempt has previously (U.S. Pat. No. 4,990,717) been made to solvethe problem by using both stirred tank and catalytic distillation withfixed catalyst bed, and separating mono-alkenylated product generatedfrom unreacted alkylbenzene and/or C4 to C5 conjugated diene present,both up-stream or downstream. Unreacted alkylbenzene and conjugateddiene obtained could then be recycled to the catalyst bed for furtheralkenylation.

Smectite clays in pillared form have previously been disclosed inItalian Patent Application No. RM 98A 000130. The publication disclosesthe preparation of catalysts comprising pillared smectite clays to whichmetal ions have been exchanged. These catalysts are used for catalysingdehydrogenation and in the alkylation reaction of benzene rings.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate the problems ofprior art and to provide a novel process for alkylating or alkenylatingthe side-chain of a substituted aromatic compound.

This, and other objects together with the advantages thereof, areachieved by the present invention as hereinafter described and claimed.

The invention is based on the finding that by using a catalystcomprising a restructured smectite clay the side-chain of substitutedaromatic compounds can be alkylated or alkenylated. The smectite clay isrestructured by treating the clay with an acid, whereupon basic ions areincorporated in the restructured smectite clay by ion-exchange.

The invention also provides novel catalysts comprising restructuredclay, which has been subjected to acid-treatment and ion-exchange.

A number of considerable advantages are obtained with the aid of thepresent invention. The catalyst used in the present process is easy tohandle. There are no safety precautions relating to the use of thepresent catalyst. Further, since there are no noxious substances in thecatalyst as such, the catalyst can easily be disposed of after reachingthe end of its utility in the present process.

The activity of the catalyst in base-catalysed reactions is sufficientlyhigh. The present catalyst is particularly advantageous in theside-chain alkylation or alkenylation of substituted aromatic compounds,where a catalyst with an even higher activity may give rise to a numberof undesired by-products. The yields of the desired products, on theother hand, are distinctly higher than by using catalysts known in theart.

When using the present process in the alkylation of the side-chain,by-products, which may also have use in other applications are formed.Tolyl aldehyde and octatrienal are essentially always formed, even in arelatively high yield of 5–30%, in particular 15–25%, and more than 10%,in particular more than 30%, respectively.

When alkylating the side-chain of xylene with butene or butadiene, theproduct is more pure than that obtained with conventional methods, thusfacilitating further processing by eliminating purification steps. Pure2-methyl-p-tolyl-butene (or -ane) obtained from the reaction betweenp-xylene and butene or butadiene can be used, e.g., for producing2,6-dimethylnaphthalene (disclosed in our co-pending application FI982630). In this kind of process the purity of the raw material, i.e.,the product obtained by the present invention, needs to be as high aspossible.

The present process allows for using lower reaction temperatures in aside-chain alkylation reaction than is taught in prior art. The presentprocess also renders it possible to operate at ambient pressure. Thepossibility of using low temperatures results in more economicalproduction and the low pressure reduces safety risks in an industrialscale process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the effect of pillaring on a smectite clay.

FIG. 2 illustrates the effect of acid-treatment on a smectite clay.

In FIG. 3 is shown an XRPD diagram for saponite and acid-treatedsaponite.

In FIG. 4 is shown an XRPD diagram for montmorillonite, acid-treatedmontmorillonite, and Ca- and Mg-exchanged acid-treated montmorillonite.

FIG. 5 illustrates the effect of the molar ratio of the startingmaterials on the yield.

FIG. 6 is a schematic picture of the configuration of a circulatoryreflux reactor.

FIG. 7 is a schematic picture of the configuration of a tubular reactor.

FIG. 8 illustrates the yields in the reaction between p-xylene and1-butene using four different catalysts.

FIG. 9 depicts an X-ray powder diffraction pattern of acid-treatedmontmorillonite Mg exchanged.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Generally, “alkylation” is used to designate the reaction in which analkyl chain is added to a compound, and “alkenylation” refers to areaction in which an alkenyl chain is added to a compound. It is obviousthat the alkylating agent is an alkene while dienes are used asalkenylating agents. For reasons of simplicity, in the followingdescription the term alkylation is used in connections where bothreactions are possible. It is to be understood that the used term isintended to cover both reactions.

“Restructured” catalyst means a catalyst treated so that its structureis altered. In the case of smectite clays this can be done by pillaring,i.e., by introducing for example oxidic particles between the layers ofthe layered smectite clay structure. Another alternative is to treat thesmectite clay with acid. The acid-treated catalysts are referred to by aprefix “H” as compared to the untreated smectite clay, for example, MOand H-MO are used to designate untreated montmorillonite andacid-treated montmorillonite, respectively.

The catalyst

The catalyst according to the present invention consists essentially ofa restructured clay, preferably a smectite clay, to which basic ions areincorporated by ion-exchange.

The smectite clays are earth-based raw materials, and examples ofsmectite clay types include montmorillonite (hereinafter MO), beidellite(B), saponite, bentonite, and mixtures thereof, such asbeidellite/montmorillonite (Zenith-N, also referred to as ZN). In thepresent process the catalysts preferably comprise montmorillonite, inparticular Texas white montmorillonite and European whitemontmorillonites (such a Altonit EF White). Smectite clay catalysts aredescribed in U.S. Pat. Nos. 6,335,405, 5,171,896, and 5,414,185.

Smectite clays are highly acidic, and they contain AlO₄ and SiO₄tetrahedra and small amounts MgO and Fe₂O₄. As an example, the chemicalformula of commercial clay Zenith-N is: (Na_(0.63)K_(0.07)Ca_(0.011))[Si_(7.75) Al_(0.25)]×(Al_(3.21) Mg_(0.69) Fe_(0.02)Fe_(0.03) Ti_(0.05))O₂₀(OH)₄.

Smectite clays have platelet morphologies of varying c-order, i.e., withvarying number of platelets stacked on one another. The catalysts usedin the process of the present invention are, as already discussed,restructured. In the following, two different ways of restructuring thecatalysts are discussed:

According to one embodiment of the invention, the smectite clays arepillared with oxidic particles. These compounds are generally known asPILC's. Any smectite clay type can be pillared with oxidic particles inorder to form a PILC. The pillaring can be carried out with, e.g.,polyhydroxyaluminium-ion-containing solution. Thus, the oxidenanoparticles between the layers of the smectite structure are typicallyalumina. Hence, the abbreviation “AlZN” refers to a Zenith-N typesmectite clay pillared with alumina nanoparticles. The presence of ironin alumina pillars in pillared clays (e.g. FAZA) seems to give rise tothe highest amounts of undesirable alkylation side-products.

The effect of pillaring on the structure of the smectite clay isillustrated in FIG. 1. The nano-particles used for pillaring are locatedbetween the layers in a smectite clay structure. The nano-particles arethen cross-linked, which leads to platelet scission.

Pillared smectite clays and process for the preparation thereof aredisclosed, e.g., in Italian Patent Application No. 98A 000130.

According to another embodiment of the present invention the smectiteclays are restructured by acid-treatment. The acid treatment is carriedout by bringing the smectite clay into contact with an acid and washingit subsequently with deionized water. The acid for acid-treatment isselected from a group comprising nitric acid, sulphuric acid orhydrochloric acid in aqueous solution. The acid-treatment according tothe present invention is mild. The mild acid-treatment means that theconcentration of the acid in the solution is 0.1–5 mol/dm³, preferably1–2 mol/dm³, and does not lead to completely disrupt plateletassociation. This can also be seen in FIG. 2, where the effect ofacid-treatment on a smectite clay structure is illustrated.

The acid-treatment is typically carried out at room temperature, but itis also possible to use temperatures in the range of 20–50° C. Theacid-treatment lasts typically at least for 1 hour, preferably for atleast 3 hours. Preferably, the acid-treatment is carried out understirring. After having been contacted with the acidic solution, the pHof the smectite clay is typically in the range of 0.1–4, in particular0.5–2.

The subsequent washing is continued until the pH of the smectite clay is4.5 or more, preferably 5 or more and in particular 5.5 or more.

The catalysts can be characterised by standard techniques, such as X-raypowder diffraction technique and atomic absorption analysis. FIG. 3shows an XRPD diagram of acid-treated saponite (H-SA) compared withstarting saponite (SA). The change of order can be noticed in FIG. 3.

In both of the methods of restructuring presented above, an open, highlyporous structure is obtained for the smectite clay. The pores in thestructure have openings which are large enough for allowing thereactants and reaction products of the alkenylation reaction passthrough.

The smectite clay used in either of the above-described embodiments ispreferably finely divided to enable a more complete acid treatment.Optionally, the smectite clay is ground e.g. in a mortar in order toreduce the particle size, and/or it is sieved so as to confirm arelatively homogeneous particle size. It is also possible to reduce theparticle size after restructuring by these processes.

The basic nature of the catalyst is achieved by ion-exchange. Thus, therestructured catalyst is subjected to ion-exchange with alkali metalcations, preferably Na⁺ and/or K⁺, or alkaline earth metal cations,preferably Ca²⁺, Mg²⁺ and/or Ba²⁺. The exchange level may vary dependingon the desired level of basicity and on the size and degree of basicityof the exchanged cation from 0.1 to 30% (w/w), preferably from 0.25 to20% (w/w) and in particular 8–15% (w/w).

According to one embodiment of the invention, the catalyst isback-exchanged, i.e., a further ion-exchange or further ion-exchange is(are) carried out subsequent to the first (second, etc.) ion-exchange.This arrangement enables tailoring the properties of the catalyst tosuite the desired reaction even better. The back-exchanged material isin the following referred to as M₁M₁₁-Z, wherein M₁ is thefirst-exchanged cation. M₁₁ is the cation exchanged subsequently and Zis the starting smectite clay structure.

After ion-exchange, the catalyst is dried in air at a temperature in therange from 15° to 100° C., preferably at room temperature.

The thus obtained catalysts are new and can preferably be used inbase-catalysed reactions, in particular in the side-chain alkylation ofsubstituted aromatic compounds.

FIG. 4 shows an XRPD diagram comparing the patterns of Texasmontmorillonite (MO), acid-treated montmorillonite (H-MO) and Mg²⁺ andCa²⁺-exchanged acid-treated montmorillonite (Mg—H-MO and Ca—H-MO,respectively).

Prior to its use in an alkylation reaction, the catalyst is activated ata temperature in the range of 50–500° C., preferably 100–250° C., inair. The use of a high activation temperature, i.e., in the range of250–500° C. results typically in high activity. A drawback is, however,the increasing of the amount of by-products at the same time. Mg—HMOactivated at approximately 250° C., however, forms an exception, sincethe activity is increased without the increase in the amount ofby-products.

The Alkylation Process

The process according to the present invention comprises the alkylationof substituted aromatic compounds in the presence of a catalystcomprising a restructured, ion-exchanged smectite clay.

The substituted aromatic compounds typically include alkylbenzenes, inparticular alkylbenzenes with a multi-, in particular di-substitutedbenzene ring. The alkylbenzenes preferably used in the process of thepresent invention are those having the general formula (I):

wherein

-   -   R₁ is methyl, ethyl, propyl, isopropyl, butyl, hydroxyl,        C₁–C₃-aldehyde or amino group, and    -   R₂ is hydrogen, linear or branched C₁–C₄-alkyl-, C₁–C₃-aldehyde,        hydroxyl- or amino group,

R₁ and R₂ being selected so that at least one of the substituentscontains at least one carbon atom.

The location of the radicals is preferably such that R₂ is inpara-position with regard to R₁.

Examples of suitable alkylbenzenes include o-, m- and p-xylene, toluene,tolyl aldehyde, aminotoluene, o-, m-, and p-cresol, and phenyl aldehyde.Of these, p-xylene and p-tolyl aldehyde are preferred.

Generally, larger hydrocarbon substituents, having 3 to 4 carbon atoms,are more susceptible to alkylation and alkenylation than substituentswith only 1 or 2 carbon atoms. Of the butyl groups, n-, iso- andtert-butyl should be mentioned.

Alkylating agents used in the present invention are selected from thegroup consisting of ethene, propene, 1- and 2-butene, isobutene and1,3-butadiene. Of these 1- and 2-butene and 1,3-butadiene areparticularly preferred. It is to be noted that the reactivity of alkenesincreases when the carbon chain becomes shorter and thus, for ethene andpropene, the temperatures used in the process can be set to even lowervalues.

According to a preferred embodiment of the present invention, thealkylation process comprises the alkylation of xylene, in particularpara-xylene, with 1- and/or 2-butene and/or 1,3-butadiene.

According to another preferred embodiment of the present invention thealkylation process comprises the alkylation of tolyl aldehyde with 1-and/or 2-butene and/or 1,3-butadiene.

The process can also be applied to the alkylation of toluene withpropylene to yield 2-methylpropyl)benzene which is a useful intermediatefor the production of Ibufenac (4-(2-methylpropyl)benzeneacetic acid),Ibuprofen (α-methyl-4-(2-methylprpyl)benzeneacetic acid) and Ibuproxam(N-hydroxy-α-methyl-4-(2-methylpropyl)benzeneacetamide).

Below is shown a reaction equation of the preferred embodiment of theinvention. In the equation below R₁ is a methyl group and R₂ is a methylor a formyl group in para-position with regard to R₁, in other words,the starting material is p-xylene or p-tolyl aldehyde. The alkylatingagent is 1- or 2-butene.

The equation shows that both 1- and 2-butene yield the same compound,i.e., 2-methyl-p-tolyl-butane. Therefore, a mixture of the two compoundscan well be used in the alkylation process without a need to productseparation. When using 1,3-butadiene in the above reaction, the reactionproduct has a double bond between the third and fourth carbon atom inthe side-chain.

For reasons of simplicity, the reaction products described above are inthe context of the present application also referred to as“para-tolyl-pentane or para-tolyl-pentene”, both abbreviated “PTP”.

The catalyst used in the reaction is described above. Particularlypreferred catalyst are Mg²⁺-exchanged catalysts, and in particular Mg²⁺exchanged montmorillonites.

The alkylation reaction is typically carried out at ambient pressure,but pressures of 0.1–10 bar, preferably 1–5 bar can also be used.

The temperature in the reactors is typically in the range of 150–500°C., preferably in the range of 150–400° C. and in particular in therange of 200–300° C. The use of high reaction temperatures gives rise tothe highest activities, but usually also to a larger number ofby-products, as a consequence, the preferred reaction temperature forexample for Mg—H-MO is approximately 250° C.

The ratio of the aromatic compound to the alkylating agent is typicallykept quite high, in other words, the amount of the alkylating agent withrespect to the amount of the aromatic compound in the reactor is low.The low amount of the alkylating agent helps to avoid the polymerisationof the alkylating agent. Typically, the molar ratio of aromatic compoundto the alkylating agent is 50 or less, preferably 5 or less and inparticular 1. It is, however, also possible to use also greater amountsof alkylating agent, for example in a molar ratio of aromatic compound:alkylating agent of 0.5 or in the range of 0.05–0.005. The effect of themolar ratio is depicted for p-xylene and butene in FIG. 5.

The reaction can be carried out operating in a batch-wise,semi-batch-wise or continuous mode. The reactor can thus be any commonstirred-tank reactor or a fixed-bed flow reactor. In the following, eachof the three operation modes is presented. As a typical example of thealkylation reaction, and one embodiment of the present invention, thereaction of p-xylene with 1- or 2-butene or 1,3-butadiene is considered.

A. Batch-Wise Operation

The reaction time in the batch- or semi-batch-wise operation is in therange from 1 min to 20 hours. Typically, the reaction time is in therange from 30 min to 8 hours, in particular from 1 to 3 hours.

Yields obtained in a batch-wise operation of p-xylene alkylation with 1-or 2-butene depend on the reaction time and are typically in the rangeof 0.1 to 30%, preferably 1–20% and in particular 2–17% (calculated withrespect to the starting amount of p-xylene).

According to the experiments made on the batch-wise production, a higherpressure in the reactor results in a higher total yield of C₁₂-products.Preferably, however, the reaction is carried out at ambient pressure.

B. Semi-Batch-Wise Operation

In the semi-batch-wise mode, the total amount of the substitutedaromatic compound is preferably fed to the reactor at the beginning ofthe reactor operation, and the alkylating agent is fed to the reactor ata predetermined flow rate during the reaction.

The reaction times in the semi-batch operation are similar to thosediscussed above for the batch-wise operation. At the reactiontemperature the reagents and the reaction product are in gaseous phase.

The reactors used in semi-batch-wise operation can be ordinary stirredtank reactors. According to a preferred embodiment of the invention thereaction is carried out in a reflux reactor with circulation. In such anarrangement, the reaction occurs in a reaction zone containing thecatalyst. A heating zone comprises typically a vessel or the like and,naturally, means for heating and controlling the temperature. Thereagents are preferably fed to the heating zone, which is arranged priorto the reaction zone, and in which the reagent(s) are vaporized. Thus,the reaction occurs in gas phase. As a reactor, an ordinary stirred-tankreactor can be used, but preferably the reactor is a tubular reactorcomprising one or several tubes. In a tubular reactor the catalyst ispreferably packed to form a bed. The gaseous starting materials react toform reaction products, and the reaction mixture containing these iscooled so that the reaction products and optionally the unreactedstarting materials are in liquid phase. The reaction products areoptionally recovered prior to feeding the reaction mixture back to theheating zone, where it is, again, gasified.

The substituted aromatic compound is preferably fed to the heating zonein its total amount at the beginning of the reaction operation. Thealkylating agent is fed to the reaction mixture, typically to theheating zone, gradually.

An example of a preferred semi-batch arrangement is shown in FIG. 6. Thecolumn 1 in which the reaction occurs is packed with catalyst. Thecolumn is typically ade of glass. The column is equipped with means forheating 4, and the reaction zone 6 is the heated part of the column 1.The temperature in the reaction zone 6 is controlled by temperaturecontrolling means 7. The first starting material is fed to the heatingzone, in other words, to a round-bottom flask-type recipient 2 locatedon heater 3. The second starting material is conducted to the recipient2 located on heater 3. The second starting material is conducted to therecipient 2 continuously or intermittently from a stock container 5.From the reaction zone 6 the gaseous reaction products together with theunreacted starting materials flow to the cooling section, in which thereaction mixture is cooled with means for cooling 8. Optionally, areservoir 9 is arranged between the cooling section and the heating zoneor the reaction zone. Samples of the reaction mixture can be taken fromthe reservoir 9. The cooled reaction mixture is then conducted back tothe recipient 2.

C. Continuous-Flow Operation

In the continuous flow reactors the residence time in the reactor is1–1000 min, preferably 5–200 min and in particular 10–100 min. Thereactor can be an ordinary CSTR, in which the catalyst is placed assuch. Preferably, the reactor is a tubular reactor with one or severaltubes in which the catalyst is located as a fixed bed.

An example of a fixed-bed reactor is shown in FIG. 7. Reactor 7 isequipped with means for heating, such as a furnace 2. The temperature inthe reactor is controlled by a temperature controller 5. The reactor canbe made of any typically used reactor material, for example quartz orsteel. The catalyst is located in a fixed bed in the reactor. Thecatalyst is held in its place by “plugs”, which can be selected fromsuch materials that are capable of permitting a gas flow but keeping thecatalyst in its place. An inert gas source 3 and a first reagent source4 are connected to the reactor. The feeding of the second reagent ispreferably carried out by using a syringe 6, if the amount of the secondreagent to be fed to the reactor is small. The reactor effluent can becollected after reactor 1 to a container 7.

The following non-limiting examples illustrate the present invention inmore detail.

EXAMPLE 1

Catalyst Preparation

In the preparation of an acid-treated, ion-exchanged catalyst, thestarting clay is acid-treated with 200 ml of 1.25 M HCl/g clay understirring overnight at room temperature. The sample is then washed withdistilled water so as to prepare an acid-treated clay with a pH of4.5–5. Thereafter, the catalyst is filtered and dried at roomtemperature in air.

The dried acid-treated catalyst is then exchanged with a group I or IImetal cation by contacting 1 g of the restructured clay with 200 ml of a0.1 M solution of the metal acetate with stirring overnight at 60–80° C.After the exchange the prepared catalyst is filtered, washed with 50 mlof distilled water and dried in air. The exchange procedure is carriedout two times.

The starting clay can be any of those described above, for examplesaponite or montmorillonite. The obtained catalyst can be characterizedwith XRPD technique. The diagram in FIG. 1 shows the curves of startingTexas montmorillonite, acid-treated montmorillonite and Ca- andMg-exchanged acid-treated montmorillonite.

SET OF EXAMPLES A

Batch-wise operation

Standard vial procedures were used for estimating catalytic activityunder static conditions. In a typical procedure, 10 mg of catalyst wasloaded into a tared 10 ml vial attached to a vacuum line and 100 μl ofp-xylene containing varying amounts of 1-butene added. In the following,“filling with 300 Torr of 1-butene” means that the pressure of the1-butene source was 300 Torr (40 kPa). Vials were closed, heated at apre-fixed temperature for various times, opened and the contentsanalysed by mass-spectrometry gas chromatograph (GC-MS), theidentifications were made by comparison with the NBS data base.

Example A1

Three 10 ml vials were loaded with 10 mg of catalyst prepared accordingto Example 1, namely Ba—HSA, MgBa—HSA, and Ca—HSA, previously activatedat 300° C. for 2 hours, and 100 μl of p-xylene, connected to a vacuumline, evacuated at liquid nitrogen temperature, and, after filling with300 Torr (40 kPa) of 1-butene, were sealed and allowed to react at 300°C. for 19 h.

The yields of PTP, calculated with respect to initial p-xylene, were0.25%, 0.35% and 0.50% for Ba—HSA, MgBa—HSA, and Ca—HSA, respectively.

Example A2

Two 10 ml vials were loaded with 10 mg of catalyst prepared according toExample 1, namely MgBa—HSA and Ca—HSA, previously activated at 200° C.for 2 hours, and 100 μl of p-xylene, connected to a vacuum line,evacuated at liquid nitrogen temperature, and, after filling with 300Torr (40 kPa) of 1-butene, were sealed and allowed to react at 200° C.for 19 h.

The yields of PTP, calculated with respect to initial p-xylene, were0.02% and 0.02%, for MgBa—HSA and Ca—HSA, respectively.

Example A3

A 10 ml vial was loaded with 10 mg of catalyst prepared according toExample 1, namely Mg—HMO, previously activated at 250° C. for 2 hours,and 100 μl of p-xylene, connected to a vacuum line, evacuated at liquidnitrogen temperature, and, after filling with 30 Torr (4 kPa) of1-butene, was sealed and allowed to react at 200° C. for 17 h.

The yield of PTP, calculated with respect to initial p-xylene, was1.60%.

Example A4

A 10 ml vial was loaded with 10 mg of catalyst prepared according toExample 1, namely Mg—HMO, previously activated at 450° C. for 2 hours,and 100 μl of p-xylene, connected to a vacuum line, evacuated at liquidnitrogen temperature, and, after filling with 30 Torr (4 kPa) of1-butene, was sealed and allowed to react at 150° C. for 17 h.

The yield of PTP, calculated with respect to initial p-xylene, was0.005%.

Example A5

Two 10 ml vials were each loaded with 10 mg of catalyst, namely Mg—HMOprepared according to Example 1 and NaY, previously activated at 450° C.for 2 hours, and 100 μl of p-xylene, connected to a vacuum line,evacuated at liquid nitrogen temperature, and, after filling with 30Torr (4 kPa) of 1-butene, were sealed and allowed to react at 200° C.for 2 h.

The yields of PTP, calculated with respect to initial p-xylene, were0.90% and 0.03%, for Mg—HMO and NaY, respectively.

Example A6

Three 10 ml vials were each loaded with 10 mg of catalyst preparedaccording to Example 1, namely Mg—HMO, previously activated at 440° C.for 2 hours, and 50 μl of p-xylene, connected to a vacuum line,evacuated at liquid nitrogen temperature, and, after filling with 100,200 and 300 Torr (13.3, 26.7 and 40 kPa) of 1-butene, were sealed andallowed to react at 320° C. for 16 h.

The yields of PTP, calculated with respect to initial p-xylene, were1.2%, 3.6% and 7.5%, for the vials filled with 100, 200 and 300 Torr(13.3, 26.7 and 40 kPa) of 1-butene, respectively.

Example A7

A 10 ml vial was loaded with 10 mg of catalyst prepared according toExample 1, namely Mg—HMO, previously activated at 440° C. for 2 hours,and 30 μl of p-xylene, connected to a vacuum line, evacuated at liquidnitrogen temperature, and, after filling with 300 Torr (40 kPa) of1-butene, were sealed and allowed to react at 320° C. for 16 h.

The yield of PTP, calculated with respect to initial p-xylene, was11.2%.

Example A8

A 10 vial was loaded with 10 mg of catalyst prepared according toExample 1, namely Mg—HMO, previously activated at 440° C. for 2 hours,and 10 μl of p-xylene, connected to a vacuum line, evacuated at liquidnitrogen temperature, and, after filling with 300 Torr (40 kPa) of1-butene, was sealed and allowed to react at 320° C. for 16 h.

The yield of PTP, calculated with respect to initial p-xylene, was16.7%.

Example A9

Four 10 ml vials were loaded with 10 mg of catalyst, namely Mg—HMOprepared according to Example 1, ZnAlZN, NaY, and ZnAlB4, previouslyactivated at 450° C. for 2 hours, and 100 μl of p-xylene, connected to avacuum line, evacuated at liquid nitrogen temperature, and, afterfilling with 15 Torr (2 kPa) of 1-butene, were sealed and allowed toreact at 330° C. for 16 h.

The yields of PTP, calculated with respect to 1-butene, were 7.0%, 2.6%,2.1%, and 0.4% for Mg—HMO, ZnAlZN, NaY, and ZnAlB4, respectively.

Example A10

Two 10 ml vials were loaded with 10 mg of catalyst, namely Mg—HMOprepared according to Example 1, and ZnAlB4, previously activated at450° C. for 2 hours, and 100 μl of p-xylene, connected to a vacuum line,evacuated at liquid nitrogen temperature, and, after filling with 15Torr (2 kPa) of 1-butene, were sealed and allowed to react at 380° C.for 16 h.

The yields of PTP, calculated with respect to 1-butene, were 7.0% and2.0%, for Mg—HMO and ZnAlB4, respectively.

A summary of the results of the above examples A1–A5 is shown in Table1.

TABLE 1 Reaction of 1-butene and p-xylene. Experimental Alkylation YieldCatalyst Conditions Products (C12) % Example NaY (^(a)450) 2h-200° C. 30.03 A5 30 mmHg (4 kPa) Mg-HMO (450) 2h-200° C. 4 0.9 A5 30 mmHg (4 kPa)Mg-HMO (450) 17h-150° C. 1 0.005 A4 30 mmHg (4 kPa) Mg-HMO (250)17h-200° C. 5 1.6 A3 30 mmHg (4 kPa) Ca-HSA (200) 19h-200° C. 1 0.02 A2300 mmHg (40 kPa) MgBa-HSA (200) 19h-200° C. 1 0.02 A2 300 mmHg (40 kPa)Ba-HSA (300) 19h-300° C. 2 0.25 A1 300 mmHg (40 kPa) MgBa-HSA (300)19h-300° C. 3 0.35 A1 300 mmHg (40 kPa) Ca-HSA (300) 19h-300° C. 3 0.5A1 300 mmHg (40 kPa) ^(a)=activation temperature

The yield is calculated with respect to the initial amount of p-xylene.

Utilising the catalyst Mg—H-MO, a series of experiments was carriedout—again in vials, and at 330° C. or (380° C.) for 16 h, in which thep-xylene: 1-butene ratio was kept at 100:1 (wt %). The results are shownin Table 2.

o-tolyl-pentane (OTP) was obtained as a by-product from the reaction ofp-xylene and 1-butene at the process conditions described above, whenusing the same catalyst and a ratio p-xylene: 1-butene=10:3.

TABLE 2 Typical vial catalytic test for Mg—H—MO (10 ml vial, 320° C., 16h) p-xylene 1-butene, 1-butene: p-xylene % yield with (μl) Torr (kPa)molar ratio relation to xylene 50 100 (13.3) 0.08 1.2 50 200 (26.7) 0.163.6 50 300 (40)  0.48 7.5 30 300 (40)  1.2 11.2 10 300 (40)  3.6 16.7

The reaction is preferably even more efficient at higher p-xylene:1-butene ratios (>500:1) with fewer side reactions. In other words, sucha feed should give complete consumption of 1-butene (100% ‘yield’ withrespect to 1-butene), but preferably the reaction would then be carriedout at non-static process conditions, such as catalytic distillation.

FIG. 8 illustrates the yields at high p-xylene: 1-butene ratios instatic experiments for Mg—HMO, Zn-AlZN, NaY and Zn-AlB4. The reactionswere carried out at 330° C., except for Zn-AlB4-catalyst the reaction ofwhich was carried out also at 380° C.

Production of PTP Using Tolyl Aldehyde

Tolyl aldehyde may also be utilised instead of p-xylene, as thesubstituted aromatic compound of the present process to obtain PTP. Aseries of vial reactions was carried out, now substituting tolylaldehyde for p-xylene, and using procedures detailed in Example A2. Theproduct shows a GC peak with a retention time near that of PTP and ayield of >20% (calculated with respect to 1-butene).

Example A11

A 10 ml vial was loaded with 10 mg of catalyst, namely Mg—HMO,previously activated at 440° C. for 2 hours, and 10 μl ofp-tolylaldehyde, connected to a vacuum line, evacuated at liquidnitrogen temperature, and, after filling with 15 Torr (2 kPa) of1-butene, was sealed and allowed to react at 330° C. for 16 h.

The yield of PTP, calculated with respect to 1-butene, was 24%.

Set of Examples B

Semi-Batch-Wise Operation

To further investigate whether 1-butene alone (without catalyst) may beinvolved in the reaction giving rise to PTP, a series of experiments wasperformed in which p-xylene and 1-butene were simply refluxed forvarying periods of time and the products were analysed using a GC. In atypical run, 1-butene was bubbled (50 ml·h⁻¹) through 50 ml of p-xylenein a standard reflux apparatus. Note that this reaction, at thistemperature (138° C.), gives rise to measurable quantities of therequired final product.

The semi-batch reactor configuration used in the examples below is acirculatory reflux reactor related to catalytic distillation andillustrated in FIG. 6.

The glass column in which the reaction occurs, was packed with 50 mg ofMg—HMO-catalyst. The round-bottom flask-type recipient on the heater wascharged with 50 ml dry p-xylene, which was then refluxed under variousconditions of 1-butene pressures. The product PTP is collected from theround-bottom-flask. The reservoir collects product as formed and viaseptum I was used to draw off samples for GC/MS analysis and check whenthe catalyst utilised is exhausted.

Example B1

The recycling catalytic reactor was filled with 50 mg of Mg—HMO,previously activated at 450° C. for 4 h. The catalyst was heated at 250°C. and p-xylene (50 ml) was heated at its boiling point. A mixturenitrogen/1-butene (100:1) was allowed to bubble into p-xylene at a flowrate of 50 ml h⁻¹. After 24 h the yield of PTP, calculated with respectp-xylene, was 0.8%.

Example B2

The recycling catalytic reactor was filled with 50 mg of Mg—HMO,previously activated at 450° C. for 4 h. The catalyst was heated at 250°C. and p-xylene (50 ml) was heated at its boiling point. A mixturenitrogen/1-butene (1:1) was allowed to bubble into p-xylene at a flowrate of 50 ml h⁻¹. After 24 h the yield of PTP, calculated with respectp-xylene, was 1.2%.

Example B3

The recycling catalytic reactor was filled with 50 mg of Mg—HMO,previously activated at 450° C. for 4 h. The catalyst was heated at 250°C. and p-xylene (50 ml) was heated at its boiling point. 1-butene wasallowed to bubble into p-xylene at a flow rate of 50 ml h⁻¹. After 24 hthe yield of PTP, calculated with respect p-xylene, was 4.5%.

Example B4

The recycling catalytic reactor was filled with 50 mg of Mg—HMO,previously activated at 450° C. for 4 h. The catalyst was heated byboiling p-xylene (50 ml). A mixture nitrogen/1-butene (10:1) was allowedto bubble into p-xylene at a flow rate of 50 ml h⁻¹. After 24 h theyield of PTP, calculated with respect p-xylene, was 0.6%.

Table 3 illustrates the effect of 1-butene pressure on the yield of PTPin a reflux reactor at 250° C. after a reaction time of 24 h.

TABLE 3 The effect of 1-butene pressure on the yield of PTP. 1-butene %yield very low (in N₂ flow) 0.8 0.5 atm (50.7 kPa) (in N₂ flow) 1.2 1atm (101 kPa) 4.5

Example C

Continuous Flow Operation

A fixed-bed reactor was set up as shown in FIG. 7. The reactor systemused in the experiment below consists of a quartz tube reactor in whichthe catalyst is charged and held in place by plugs. A septum at one endallows a syringe to be inserted to provide controlled amounts ofp-xylene and also to draw off samples for analysis. Controlled amountsof 2-butene are supplied via standard graduated glassware as shown.Product is collected in the reservoir equipped with a flow-meter.

Example C1

The fixed bed reactor was filled with 500 mg of Mg—HMO, heated at 450°C. and activated under nitrogen flow for 2 hours. 5 ml of p-xylene wasslowly (1ml/min) injected in the reactor together with a nitrogen/butene(95:5) mixture whose flow rate was 0.1 l/h. The products were collectedat the end of reactor and the yield of PTP, calculated with respect toinitial p-xylene, was 0.2%.

Example 2

Catalyst Preparation

Altonit EF White (EFW) from IKO-Erbslöh GmbH was used as parent clay inthe preparation of the Mg—H-MO and Mg-MO catalysts.

A sample of EFW (20 g starting clay) was treated with 200 ml of 0.05MHCl/g clay under stirring for 3 hours at room temperature. The samplewas then decanted and distilled water was added to reach the previousvolume regardless of the pH (3÷5). The sample was subsequently exchangedwith a group I or II metal acetate by adding 20 mmol of metal acetateper g of restructured clay and stirring overnight at 60–80° C. After theexchange the sample was filtered, washed with 50 ml of distilled waterand air dried. The exchange was repeated twice.

The magnesium uptake, as determined by AA, depends on the acidconcentration used in restructuring the clay corresponding to a higheracidity a larger uptake. It was in the range 18–14%. When MO wasexchanged with magnesium in the absence of acid treatment, with the sameprocedure reported above, the magnesium uptake was 7.5%.

The catalysts were characterized by standard X-ray powder techniques(Ni-filtered, Cu—K_(α) radiation) and atomic absorption analysis. FIG. 9shows the XRPD of mild acid-treated EFW (sample 16).

Example D

Four catalysts were prepared using different HCl concentrations inmontmorillonite treatment before the magnesium exchange.

-   Catalyst 1: HCl 0.5 M-   Catalyst 2: HCl 0.1 M-   Catalyst 3: no acid-   Catalyst 4: HCl 0.05 M

To compare the catalytic properties of the above 4 catalysts they havebeen tested in vials following the procedure described above. To aweighed amount (10 mg) of catalyst activated at 440° C., a known amountof p-xylene (100 μl) were added together with 300 torr (40 kPa) of1-butene, sealed under vacuum, and allowed to react at 280° C. for 16hours.

The obtained results are shown in Table 4:

TABLE 4 Yield of alkenylation reaction calculated with respect top-xylene (vials experiments) Catalyst HCI concentration Yield Mg-HMO 0.1 M 0.37% Mg-HMO  0.5 M 1.03% Mg-HMO 0.05 M 6.97% MG-MO 2.10%

The yields of the products are somewhat lower than obtainable with acatalyst derived from Texas montmorillonite, however the reactionproduct is very clean which provides for the use of a process withcontinuous or intermittent recirculation of the unreacted reactants toincrease the yield.

1. A process for alkylating or alkenylating a side-chain of asubstituted aromatic compound, said process comprising restucturing asmectite clay by acid-treating or pillaring, incorporating basic ionsinto the restructured smectite clay by ion-exchange, and reacting thesubstituted aromatic compound with one of an alkylating agent and analkenylating agent in the presence of a catalyst, wherein said catalystcomprises said restructured smectite clay into which said basic ionshave been incorporated.
 2. The process according to claims 1, whereinthe pillared structure comprises oxidic nanoparticles.
 3. The processaccording to claim 1, wherein the ion that is exchanged is selected fromthe group consisting of alkali metal ions, alkaline earth metal ions andZn²⁺ ions.
 4. The process according to claim 3, wherein the ion that isexchanged is selected from the group of Na⁺, K⁺, Ca²⁺, Mg²⁺, Ba²⁺ andZn²⁺ ions.
 5. The process according to claim 1, wherein the smectiteclay is selected from the group consisting of saponite, montmorillonite,beidellite, bentonite and mixtures thereof.
 6. The process according toclaim 1, wherein the catalyst comprises acid-treated montmoriloniteexchanged with Mg²⁺ ions.
 7. The process according to claim 1, whereinthe one of an alkylating agent and an alkenylating agent is an aliphaticunsaturated compound.
 8. The process according to claim 7, wherein theone of an alkylating agent and an alkenylating agent is one of a linearand a branched C₂–C₁₀.
 9. The process according to claim 8, wherein theone of an alkylating agent and an alkenylating agent is one of a C₃–C₈alkene and a C₃–C₈ diene.
 10. The process according to claim 7, whereinthe one of an alkylating agent and an alkenylating agent is one of1-butene, 2-butene, and 1,3-butadiene.
 11. The process according toclaim 1, wherein the substituted aromatic compound is an alkylbenzene.12. The process according to claim 11, wherein the alkylbenzene has thegeneral formula (I)

wherein R₁ is one of methyl, ethyl, propyl, isopropyl, butyl,C₁–C₃-aldehyde, hydroxyl and amino groups, and R₂ is one of hydrogen,linear C₁–C₄-alkyl-, branched C₁–C₄-alkyl-, C₁–C₃-aldehyde, hydroxyl andamino groups, R₁ and R₂ being selected so that at least one of thesubstituents contains at least one carbon atom.
 13. The processaccording to claim 12, wherein R₁ is a methyl group and R₂ is a methylgroup.
 14. The process according to claim 12, wherein R₁ is a methylgroup and R₂ is a CHO-group.
 15. The process according to claim 12,wherein R₂ is in para-position with regard to R₁.
 16. The processaccording to claim 1, wherein the substituted aromatic compound isp-xylene and the alkylating agent is at least one of 1-butene, 2-buteneand 1,3-butadiene.
 17. The process according to claim 1, wherein theprocess is carried out in a reflux reactor with circulation.